U.S. special envoy Jason Greenblatt attends the launch of a project to improve access to wastewater treatment and water for Palestinian farmers, Oct. 15, 2017, in the city of Jericho, in the Israeli-occupied West Bank.
FILE - Jason Greenblatt, center, U.S. President Donald Trump's Middle East envoy, arrives to visit Kibbutz Nahal Oz, just outside the Gaza Strip, in southern Israel, Aug. 30, 2017.

UNITED NATIONS - It's been called the Deal of the Century by U.S. President Donald Trump, but it's still a tightly held secret in Washington.

Trump's son-in-law and key adviser Jared Kushner and special negotiator Jason Greenblatt have been working on the Israeli-Palestinian peace project for two years.

On Tuesday, Greenblatt addressed the U.N. Security Council, disclosing only that the document is 60 pages long.

Afterward, he told a small group of reporters that he is ready for "withering criticism" once the plan is revealed, which he says is likely to be in the next few months.

FILE - White House senior adviser Jared Kushner speaks in Manama, Bahrain, June 25, 2019.

"We are going to air it at a time when we think it has the best chance of success," Greenblatt said. "I really hope it doesn't take beyond the Israeli election/government coalition."

Israel is facing new parliamentary elections in mid-September after Prime Minister Benjamin Netanyahu was unable to form a coalition government after winning April's election.

Palestinian stance

Greenblatt says he and Kushner have talked to wide swaths of Israeli and Palestinian society in creating their proposal, including political and religious leaders, academics, experts and ordinary citizens. They have also gathered input in regional capitals and in Europe.

"I don't think there will be many surprises in the plan," Greenblatt said. "We test ideas, we see the reactions ... we know where the hot buttons are."

The Palestinian Authority has essentially rejected the plan sight unseen after Trump recognized Jerusalem as the capital of Israel in December 2017 and moved the U.S. embassy there last year. The city, holy to Jews, Muslims and Christians, has been for decades one of the most sensitive final status issues.

FILE - U.S. President Donald Trump's daughter Ivanka Trump, left, and U.S. Treasury Secretary Steve Mnuchin unveil an inauguration plaque during the opening ceremony of the new U.S. embassy in Jerusalem, May 14, 2018.

The U.S. negotiator hopes the Palestinians will soften their stance once the plan is released.

"It would be tragic for the Palestinian people themselves if their leadership just chooses to ignore it," he said.

Iran factor

But Greenblatt is betting on there being enough "exciting things" in the political plan to persuade the Palestinians to come to the negotiating table, although an effort to get them to Bahrain in June for the roll out of potentially $50 billion in economic incentives was unsuccessful.

He adds that while one of the biggest challenges in the plan is Israel's security, another is a potential spoiler.

"Even if I had a great peace plan, if we don't figure out to make sure that Iran doesn't spoil it, how much success are we really going to have?" he asked, noting that peace between Israel and the Palestinians is Iran's "worst nightmare."

Greenblatt and Kushner are scheduled to return to the region next week and will be joined by the administration's point man on Iran policy, Brian Hook.